Patent document 1 discloses a power transfer control device that is applied to a vehicle including an in-vehicle power storage device, which transfers power to and from an external power source, and a communication unit for transferring power. When an antitheft device installed in a plug-in vehicle detects an abnormality, the power transfer control device interrupts the charging of an in-vehicle battery from the external power source and instructs an ECU that controls the car air conditioner to perform maximum output operation. This increases the discharging of the in-vehicle battery.
When charging the in-vehicle battery from the external power source, there is a technique that uses a communication line, in addition to a charge cable, to connect the vehicle and the external power source and transfer a control pilot signal (CPLT signal) that controls charging.
Patent document 2 describes performing in-band communication that exchanges more information than information included in the CPLT signal by superimposing a high frequency signal, which has a higher frequency than the CPLT signal, on the CPLT signal.
A standard for in-band communication regulates that communication is to be interrupted in at least one of a vehicle side and an external power source side when a communication abnormality occurs. If a power transfer control device such as that described in patent document 1 increases discharging of the in-vehicle battery when a communication abnormality occurs, the following problems occur. When charging is desired and a communication abnormality occurs, the charging rate of the in-vehicle battery may be excessively decreased. In addition to a device that performs in-band communication, a device that transfers power while communicating with an external power source may consume storage charge of the in-vehicle battery in an unnecessary manner when a communication abnormality occurs.